Katie Baxter was 52 days old when she was brought to All Children's Hospital in St. Petersburg with severe injuries to her head. She spent the next 62 days there before she died on Feb. 4. She was barely 4 months old.

On Thursday, the Pasco Sheriff's Office said Katie was murdered. The cause of death: blunt force trauma. They arrested her father, Shawn Gordon Baxter, saying he was responsible.

Baxter, a 30-year-old sex offender, had been staying with his mother in Texas, said Pasco sheriff's spokesman Kevin Doll. Baxter was arrested Wednesday in Bryan, about 100 miles northwest of Houston. He's awaiting extradition to Pasco.

Doll released few details about the circumstances surrounding Katie's fatal injury, citing an active investigation.

Pasco deputies responded to Baxter's home at 15802 Olney Lane in Shady Hills on Dec. 4 and found the baby in medical distress. The medical examiner eventually determined that the cause of death was homicide.

"My whole life has been a struggle," Baxter wrote to a Manatee judge in 2006, when he was contesting a violation of probation charge. "From watching family drinking, fighting (physical and verbal) to watching my mother get beat with whatever in arm's length. That is where a lot of my bad ways and manners come from."

He said he spent his life rebelling against the law.

"I was just a young punk trying to show 'my friends' I was 'cool.' I wasn't cool," he wrote. "I was stupid."

Neighbors on Olney Lane said Baxter lived with his wife, Octavia Nichole Baxter, and his mother-in-law. Days after Katie's injury, Octavia Baxter filed a domestic violence injunction against her husband, who also has charges pending in Manatee County. He is accused of forcing himself sexually on a 58-year-old woman and breaking her collarbone in several places, court records state. Baxter also faces multiple counts of sexually assaulting a 12-year-old, according to the Florida Department of Law Enforcement.

He has served two stints in prison, totaling more than six years, according to the Florida Department of Corrections.

In 2000, Baxter was convicted of lewd or lascivious exhibition on a victim younger than 16, according to the FDLE. In 2005 he was convicted of lewd or lascivious battery on a victim age 12 to 15, according to the agency. Both crimes happened in Manatee County. He was also convicted of failing to register as a sex offender.

Baxter registered in March as a sex offender in Texas, so he was not difficult to find, Doll said. The agency had to wait for a cause of death from the medical examiner's office, which is why there was a delay between Katie's death and Baxter's arrest, Doll said. He did not know when Baxter would be brought back to Pasco.

Octavia Baxter and her mother have moved from the Shady Hills home, neighbors said. On Thursday, it appeared vacant.

Times researcher Caryn Baird contributed to this story. Erin Sullivan can be reached at esullivan@tampabay.com or (727) 869-6229.